Patent Application
20130078132
1. Field of the Invention
The present invention relates to an integral forming method for a composite metal and, more particularly, to an integral forming method for use in metals having different properties or alloys having different specific gravities.
2. Description of the Related Art
In a forming method of the weight 92, the weight outer layer 921 is produced by using a casting technique, and a pressing technique is used to bond metal powders of the weight inner layer 922 with the weight outer layer 921. The weight inner layer 922 takes shape by using a sintering technique. Finally, the weight 92 is fixed to the body 91 by welding.
However, the forming method of the weight 92 includes casting of the weight outer layer 921 as well as pressing and sintering for bonding the weight inner layer 922 with the weight outer layer 921 as an integral member. Namely, the processing is inconvenient, because casting, pressing, and sintering are required.
Furthermore, when forming the weight outer layer 921 and the weight inner layer 922, the formation property requirements for materials are different due to different processing characteristics of casting and sintering. As an example, when the weight outer layer 921 and the weight inner layer 922 are produced with alloys having an identical properties and having different specific gravities, the formation properties of the alloys must be suitable for both of casting and sintering. However, not all alloys are suitable for both of casting and sintering, leading to limitation to choices of the materials for current forming methods.
Furthermore, in the forming method of the weight 92, pressing and sintering of the weight inner layer 922 are carried out after casting the weight outer layer 921. Namely, the weight outer layer 921 and the weight inner layer 922 are not integrally formed at the same time, leading to insufficient the bonding strength between the weight outer layer 921 and the weight inner layer 922.
An objective of the present invention is to provide an integral forming method for a composite metal to simplify the processing procedures, providing convenient production.
Another objective of the present invention is to provide an integral forming method for a composite metal to allow more choices of materials for the composite metal.
A further objective of the present invention is to provide an integral forming method for a composite metal to increase the bonding strength of the composite metal.
An integral forming method for a composite metal according to the present invention includes a preparation step including preparing powders of at least two metals or alloys; a formation step including pressing powders of one of the at least two metals or alloys into a single blank by pressing molding, and then pressing the single blank and the powders of a remainder of the at least two metals or alloys into a composite metal blank; and a sintering step including sintering the composite metal blank into a composite metal product.
An integral forming method for a composite metal according to the present invention includes a preparation step including preparing powders of at least two metals or alloys; a formation step including injecting powders of one of the at least two metals or alloys into a mold to form a single blank by metal injection molding, and then placing the single blank in another mold and injecting the powders of a remainder of the at least two metals or alloys into the other mold to form a composite metal blank; and a sintering step including sintering the composite metal blank into a composite metal product.
The advantageous effects of the present invention are that, by using the integral forming method for a composite metal according to the present invention, one-time sintering is carried out after formation of the composite metal blank from the powders of at least two metals or alloys to sinter the powders of at least two metals or alloys into the composite metal product. The processing procedures are simplified, and the production is easier. By using the integral forming method for a composite metal according to the present invention, after formation of the composite metal blank from the powders of at least two metals or alloys, the composite metal blank is integrally sintered into the composite metal product, allowing production by a single processing procedure. Suitability of the materials to the processing methods is less important, providing less limitation to the choices of materials. By using the integral forming method for a composite metal according to the present invention, after formation of the composite metal blank from the powders of at least two metals or alloys, the composite metal blank is integrally sintered into the composite metal product, such that a recrystallization layer is formed on surfaces of the at least two metals or alloys, enhancing the mechanical strength and bonding strength between the powders of metals or alloys.
wherein:
The above and other objectives, features, and advantages of the present invention will become clearer in light of the following detailed description of preferred embodiments of the present invention described in connection with the accompanying drawings.
With reference to
The preparation step S1 includes preparing powders of at least two metals or alloys, such as powders of at least two pure metals having different properties, powders of at least two alloys having different properties, or powders of at least two alloys having the same properties and having different specific gravities. Specifically, the preparation step S1 can be machining, milling, atomization, granulation, electrolytic decomposition, or a reduction method for turning at least two metals having differing properties into powders to obtain the powders of at least two pure metals having different properties. In preparation of powders of at least two alloys having different properties or having different specific gravities, powders made from several pure metals are mixed according to the desired ratio to obtain powders of at least two alloys having different properties or to obtain powders of at least two alloys having the same properties and having different specific gravities. Furthermore, at least two alloys having different properties or having different specific gravities can be prepared and then turned into powders to obtain powders of at least two alloys having different properties or to obtain powders of at least two alloys having the same properties and having different specific gravities.
The formation step S2 includes forming a composite metal blank from the at least two metals or alloys by pressing molding (PM) or metal injection molding (MIM). Specifically, in pressing molding (PM) for producing the composite metal blank from the powders of the at least two metals or alloys, a plurality of molds is used to proceed with a plurality of pressing molding procedures on the powders of the at least two metals or alloys to form the composite metal blank. As an example, when producing the composite metal blank from powders of two pure metals having different properties by pressing molding, the powders of one of the metals are filled into a mold and pressed into a single blank. The single blank is placed into the other mold, and the powders of the other metal are filled into the other mold for pressing molding. The powders of the at least two metals or alloys are pressed and synthesize with each other to form the composite metal blank. The pressing molding is carried out at a predetermined pressure that varies according to the properties of the metal powders to be pressed. Preferably, the predetermined pressure is in a range of 20-100 tons.
In metal injection molding (MIM) for producing the composite metal blank from the powders of the at least two metals or alloys, a plurality of injection molds is used to proceed with a plurality of metal injection molding procedures on the powders of the at least two metals or alloys to form the composite metal blank. As an example, when producing the composite metal blank from powders of two pure metals having different properties by metal injection molding, the powders of one of the pure metals are injected into an injection mold to form a single blank. The single blank is placed into the other mold, and the powders of the other pure metal are injected into the other mold. The powders of the two pure metals having different properties synthesize with each other in the other mold to form the composite metal blank. Furthermore, a polymer can be added into the powders of the two pure metals having different properties and serves as a binder during metal injection molding, increasing the bonding strength between the powders of the two pure metals having different properties. The polymer can be polyvinyl alcohol, polyvinyl acetate, or a wax-based binder. The polymer is preferably a wax-based binder and, more preferably, paraffin.
The sintering step S3 includes sintering the composite metal blank into a composite metal product. Specifically, in the sintering step, the composite metal blank is heated to a predetermined temperature for a predetermined period of time, such that a recrystallization layer is formed on surfaces of the composite metal blank produced from the at least two metals or alloys, enhancing the mechanical strength and bonding strength between the powders of metals or alloys. A composite metal product is, thus, integrally formed. The predetermined temperature in the sintering step S3 varies according to the properties and specific gravities of the powers of the at least two metals or alloys. Furthermore, the predetermined temperature is lower than the melting points of the powders of the at least two metals or alloys. When sintering powders of two metals or two alloys having different melting points into the composite metal product, the predetermined temperature is lower than the melting point of the powders of the metal or alloy with a lower melting point and is preferably 1370-1450° C. Preferably, the predetermined period of time in the sintering step S3 is an hour. Furthermore, when sintering powders of two alloys having the same properties and having different specific gravities, the predetermined temperature varies according to the specific gravities of the alloy powders. The larger the specific gravities of the alloys, the higher the melting point. Namely, the larger the specific gravities, the higher the predetermined temperature.
Furthermore, in the sintering step S3, a reductive gas can be used to avoid formation of harmful oxide layers at high temperature, avoiding oxidation of the powders of metals or alloys due to contact with the atmosphere.
The integral forming method for a composite metal according to the present invention can further include a binder removal step S4 after the formation step S2. Specifically, in a case that the formation step is metal injection molding (MIM), a polymer is added into powders of two metals or alloys and serves as a binder during metal injection molding to increase the bonding strength between the powders of the metals or alloys. The binder removal step S4 can be carried out after the formation step S2 to remove the binder. The binder removal step S4 can remove the binder by heating.
The integral forming method for a composite metal according to the present invention can further include a surface trimming step S5 after the sintering step S3. Specifically, the surface trimming step S5 includes trimming the surfaces of the composite metal product by machining, grinding, or cutting, obtaining the desired accessory.
The integral method according to the present invention can be used to produce various composite metal accessories. As an example, in production of a weight having dual specific gravities for a golf club head, the preparation step S1 is firstly carried out to produce W—Fe—Ni alloy powders having two different specific gravities. Then, the formation step S2 and the sintering step S3 are carried out to form the weight having dual specific gravities. Detailed operations of the preparation step S1, the formation step S2, and the sintering step S3 have been descried hereinbefore.
Since the weight is made of W—Fe—Ni alloys having dual specific gravities and includes an outer layer and an inner layer, the outer layer can be formed from a W—Fe—Ni alloy having a low specific gravity (9.3-14 g/cm3), and the inner layer can be formed from a W—Fe—Ni alloy having a high specific gravity (14-18 g/cm3). Thus, when the weight made of W—Fe—Ni alloys having dual specific gravities is welded to a golf club head, problems of welding difficulties and easy generation of cracks resulting from the high melting points of high specific gravity alloys are overcome. Also, the color difference between the high specific gravity alloy and the golf club body is avoided.
In view of the foregoing, in the integral forming method for a composite metal according to the present invention, one-time sintering is carried out after the formation step S2 of forming the composite metal blank from the powders of at least two metals or alloys to sinter the powders of at least two metals or alloys into the composite metal product. The processing procedures are simplified, and the production is easier.
In the integral forming method for a composite metal according to the present invention, after formation of the composite metal blank from the powders of at least two metals or alloys, the composite metal blank is integrally sintered into the composite metal product, allowing production by a single processing procedure. Suitability of the materials to the processing methods is less important, providing less limitation to the choices of materials.
In the integral forming method for a composite metal according to the present invention, after formation of the composite metal blank from the powders of at least two metals or alloys, the composite metal blank is integrally sintered into the composite metal product, such that a recrystallization layer is formed on the surfaces of the at least two metals or alloys, enhancing the mechanical strength and bonding strength between the powders of metals or alloys.
Although preferred embodiments have been illustrated and described and not intended for limiting purposes, numerous modifications and variations to the above embodiments are still possible to one skilled in the art without departing from the essence of the invention. The scope of the invention is limited by the accompanying claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201110285178.1 | Sep 2011 | CN | national |
